Volva

The volva is what remains of the universal veil (Lat. velum universale), which tightly wrapped the young mushroom while it was still underground. When the fruiting body breaks through to the surface, the lower part of this membrane stays at the base of the stem as a sac-like cup. David Arora, in “Mushrooms Demystified,” describes the volva as one of the most important features for field identification — and one of the most dangerous when ignored.

The volva is often partly or completely hidden in the soil. Roger Phillips in “Mushrooms” and Arora both insist: never cut a mushroom — pull it out whole, carefully digging around the base of the stem. Otherwise the key feature stays in the ground, and identifying the species becomes impossible.

In most Amanita species (amanitas), the volva is white, free and baggy, with an uneven, lobed edge — that's how both Zerova in the “Key to the Fungi of Ukraine” and Phillips describe it. This genus is the main “bearer” of the volva and, at the same time, the main source of fatal poisonings: the death cap (Amanita phalloides) and the destroying angel (Amanita virosa) are responsible for more than 90% of mushroom deaths in Europe. Caesar's mushroom (Amanita caesarea) also has a well-developed white, baggy volva — and it is an edible delicacy, but it is listed in the Red Data Book of Ukraine, so picking it there is prohibited.

A volva is found in mushrooms of other genera too. The paddy straw mushroom (Volvariella volvacea) is an edible mushroom that grows on straw and organic debris and is widely cultivated in Asia; Phillips describes its volva as a well-developed grayish-brown cup. Genera with a volva also include Volvopluteus and some species of Conocybe and Leucocoprinus (Index Fungorum).

For a forager, the practical takeaway is simple: any mushroom with a cup at the base of its stem needs careful identification down to species. That's no reason to skip a trip to the forest — but it is a reason to stop, pull the mushroom out whole and compare it with a trusted field guide. As Arora writes: “If in doubt, leave the mushroom in the forest.”